It is well known to package and store articles, particularly food products, in receptacles in which substantially all of the atmosphere has been removed, and a number of methods are available in the prior art to accomplish this end. In some processes the product is placed in a bag, the mouth of the bag is gathered around the vacuum nozzle while the vacuum acting through the nozzle withdraws the air from the bag, and after evacuation is completed the bag is either clamped shut with a metal clip or heat welded shut. An example of a vacuum nozzle used in this method is shown in U.S. Pat. No. 3,722,558 issued Mar. 27, 1973 to Paul W. Worline. A related automated process utilizing a plurality of vacuum nozzles is disclosed in U.S. Pat. No. 3,795,085 issued on Mar. 5, 1974 to L. George Andre, et al. However, the method utilizing a vacuumizing nozzle has proven to be unsatisfactory because a complete evacuation of the bag is difficult to obtain because the product, such as meat, is usually damp and tends to cling to the bag walls so that surface crevices in the meat will form a pocket with the bag which blocks the passage of air out of the bag during the vacuumizing process.
Other prior art methods for the vacuum packaging of fresh and frozen food products such as beef, poultry, ham, cheese, etc. employ a vacuum chamber into which a filled bag is placed in open condition. The chamber is subsequently evacuated so as to evacuate the bag. The bag is then sealed or closed within the chamber. An apparatus for carrying out such a process is disclosed in U.S. Pat. No. 3,832,824 issued Sept. 3, 1974 to William E. Burrell. However, the immediately foregoing apparatus merely provides a stationary chamber for evacuation of a single package at a time, providing a very slow production rate and high labor cost.
Another prior art method and apparatus for evacuating a filled bag within a vacuum chamber is disclosed in U.S. Pat. No. 3,693,314 issued Sept. 26, 1972 to Philip L. Reid, et al. While Reid, et al attempted to increase the production rate by evacuating two packages at a time and closing and clipping the packages within the evacuation chamber, the cycle time has proven to be extremely long and the production rate still slow.
Another prior art method and apparatus for evacuating a filled bag is the deep draw machine or process. The deep draw machine has, however, proven to be unsatisfactory because it is limited to use with products of constant size, i.e., it is not capable of handling large products in a variety of product sizes, and the closing or sealing of the bags is by way of a heat seal, which does not provide an effective seal.
Still a further prior art method relating to the evacuation and sealing of food products, such as meat and poultry, cheese and other foods, is disclosed in U.S. Pat. No. 3,851,437 issued Dec. 3, 1974 to Thomas E. Waldrop, et al. While the Waldrop, et al. device provides a vacuum chamber within which the product bags are evacuated, it has a major shortcoming in that the products are closed outside of the vacuum chamber. Such procedure is very time consuming and substantially limits the speed at which the product may be packaged.